Packages of the blister pack type have gained wide popularity due to their simplicity of design, their economy of production, and further due to the fact that they provide unimpeded viewing of the contents of the blister pack, serving as an inducement to purchasers at the very point of sale. Blister packs typically comprise a substantially dish-shaped plastic sheet which defines a recess adapted to receive the article, or articles, to be contained therein and having a continuous flange surrounding the aforesaid recess. The continuous flange is affixed to a cover sheet preferably formed of a stiff paper board or cardboard sheet, the flange being affixed thereto by heat-sealing, stapling or a suitable epoxy or adhesive. The cover sheet substantially completely seals the recess so that the transparent sheet and cover member cooperate to substantially completely surround the article, or articles, contained therein.
The transparent member may be formed of a relatively rigid plastic material, having a shape that may or may not conform to the shape of the contents and defining an interior region which enables the contents to experience at least some free movement therein. Alternatively, the transparent sheet may be of the shrink wrap type which is affixed to the aforementioned cover sheet and which is then heat treated. Shrink wrap material of this type undergoes a significant amount of shrinkage as a result of the aforesaid heating, causing the shrink wrap material to draw itself tightly against the article contained therein and to follow the shape and contours thereof thereby providing a compact package of minimal package dimensions relative to the article itself.
The variety of articles which have been packaged in blister packs is legion. One category of items which have been advantageously packaged in blister packs comprise elongated articles and especially slender, elongated articles such as replacement saw blades. The blister pack utilized to package individual saw blades, for example, comprise a substrate or cover sheet formed of an elongated relatively stiff material such as paper board and dimensionally at least slightly longer than the length of the saw blade and slightly wider than the width of the saw blade, which is positioned thereon to provide a continuous marginal portion of said substrate extending beyond the periphery of the saw blade. The transparent plastic sheet of the shrink wrap type is positioned upon the saw blade and is dimensionally of substantially the same size as said substrate and has its continuous marginal portion secured to the aforesaid marginal portion of said substrate. The transparent sheet is then treated to cause it to shrink and thereby be drawn tightly against the saw blade positioned between the substrate and the transparent sheet. The package neatly positions the saw blade and is more than adequate to retain the saw blade therein. However, the package has the disadvantage that it is wasteful of material since the substrate and the backing member must be dimensionally larger than the contents thereof in order to completely enclose the saw blade.